1. Field of the Invention
The present invention relates to a liquid discharge recording head that forms liquid droplets by discharging liquid, such as recording liquid, from discharge ports (orifices).
2. Related Background Art
A recording apparatus that is provided with functions such as those of a printer, a copying machine, a facsimile equipment, or the like, or a recording apparatus that is used as the output equipment for complex electronic equipment or a work station including a computer or a word processor, is structured to record information, such as images, on a recording sheet, a thin plastic plate, or other recording medium in accordance with recording information. Recording apparatuses of the kind are classified into ink jet type, wire-dot type, thermal type, laser beam type, and others according to the recording method that such recording apparatus adopts.
Here, in accordance with FIG. 21 to FIG. 24, the description will be made of one modal example of a liquid discharge recording head in which recording liquid is supplied from a recording liquid storing chamber that is set apart, and also, one modal example of a liquid discharge recording head having an exchangeable recording liquid storing unit mounted thereon, as typical structures of the liquid discharge recording head of the ink jet type.
FIG. 21 and FIG. 22 are views that illustrate the mode of the liquid discharge recording head in which recording liquid is supplied from an external recording liquid storing chamber through a tube member or the like. FIG. 21 is a partially broken perspective view that shows the liquid discharge recording head. FIG. 22 is an exploded perspective view that shows the liquid discharge recording head.
In the recording unit 1140, the recording element base plate 1107 provided with recording elements 1106, which are energy generating members for discharging recording liquid, is die bonded to the supporting base plate 1110 of aluminum, ceramics, or the like.
On the other hand, the wiring base plate 1108 is bonded to the supporting base plate 1110, beside the recording clement base plate 1107, in order to make electrical connection with the liquid discharge recording apparatus, and the recording element base plate 1107 and the wiring base plate 1108 are electrically connected by wire bonding, lead bonding, or the like.
In this respect, on the recording element base plate 1107, driving shift registers and a wiring pattern are arranged in addition to the recordingelements. These are incorporated in advance on the recording element base plate 1107 together with the recording elements by silicon formation technologies and techniques.
Also, for the wiring base plate 1108, a contact pad (not shown) is formed to make electrical connection with the liquid discharge recording apparatus. The recessed flow path 1103 and the liquid chamber 1104 formed on the ceiling plate 1100 are provided for the orifice plate 1101, and communicated with the fine discharge port group 1102 for discharging liquid droplets.
The ceiling plate 1100 is fixed to the recording element base plate 1107 by a flat spring 1105 or some other pressure means or by bonding means, such as a bonding agent. The liquid flow paths 1103 and the liquid chamber 1104 are partitioned. Also, the orifice plate 1101 is aligned and fixed to the bonding end faces of the ceiling plate 1100 and recording element base plate 1107.
The flow path formation member 1120 for supplying recording liquid to the liquid chamber 1104 in the ceiling plate 1100 is connected with the supply port 1122 arranged for the upper face of the ceiling plate 1100. Further, a porous member 1121 is bonded to the side where the flow path formation member 1120 faces the bonding portion of the ceiling plate 1100, thus removing impurities, dust particles, and other matter contained in the recording liquid or the like.
Here, as described above, besides the mode in which the orifice plate 1101 is bonded as a separate member, there is a mode in which it is formed by patterning as employed in semiconductor film formation.
On the other hand, the recording liquid supply member 1150 is formed by the frame member 1130 having a common liquid chamber (not shown) provided therefor to retain recording liquid therein. The frame member 1130 functions as a housing to hold the recording unit 1140.
Then, the recording unit 1140 is positioned and fixed to the frame member 1130 by use of screws 1131 or bonding means, such as a bonding agent. Further, the bonding portion thereof is sealed by sealant or the like, thus airtightly closing it.
When recording liquid is supplied to the common liquid chamber from an external recording liquid storing tank (not shown) for the liquid discharge recording head of the kind, liquid supply is effectuated through the supply portion 1132 and exhaust portion 1133 arranged in the side face of the frame member 1130. In other words, a needle-type member, such as a needle, which is provided for the liquid discharge recording apparatus, is arranged to penetrate the supply portion 1132 and the exhaust portion 1133, respectively, and then, the structure is arranged so that the air in the common liquid chamber is suctioned and exhausted through the exhaust portion 1133 to increase the negative pressure in the common liquid chamber, thus suctioning recording liquid into the common liquid chamber from the external recording liquid storing tank through the supply portion 1132.
As described above, recording liquid retained in the common liquid chamber is supplied to the nozzle portion through the flow path formation member 1120 and the ceiling plate 1100. The liquid discharge recording head shown in FIG. 21 is of the mode in which a single recording element base plate 1107 is bonded to the supporting base plate 1110. However, as another mode of the liquid discharge recording head, there is the one in which plural recording element base plates 1107 are bonded to the supporting base plate 1110. Also, in the case of a liquid discharge recording head in which a single recording element base plate 1107 is assembled, there are the liquid discharge recording apparatus in which a single liquid discharge recording head is mounted thereon, and the liquid discharge recording apparatus in which plural liquid discharge recording heads are mounted thereon.
FIG. 23 and FIG. 24 are views that illustrate the mode of the liquid discharge recording head in which an exchangeable recording liquid storing unit is mounted thereon. FIG. 23 is a perspective view that schematically shows the liquid discharge recording head. FIG. 24 is a plan view that shows the upper part of the liquid discharge recording head. As shown in FIGS. 23 and 24, the liquid discharge recording head on which an exchangeable recording liquid storing unit is mounted is formed by connecting the recording unit 1201 and the holder 1202. Then, the exchangeable recording liquid storing unit 1301 is made freely attachable to and detachable from the holder 1202. Then, recording liquid is supplied to the recording unit 1201 when the exchangeable recording liquid storing unit 1301 is mounted on the holder 1202, and then, the supply port 1302 of the exchangeable recording liquid storing unit 1301 is connected with the porous member 1203, which is arranged for the recording unit 1201 to trap dust particles.
As described above, the liquid discharge recording head that uses an electrothermal converting element has a pressure chamber in which the electrothermal converting element is provided, and then, thermal energy is given to the recording liquid by the application of electric pulses that serve as electric signals. Thus, the bubbling pressure at the time of bubbling recording liquid (at the time of giving film boiling thereto), which is generated by a phase change of the recording liquid, is utilized for discharging recording liquid droplets.
Further, for the liquid discharge recording head that uses an electrothermal converting method, there are the method in which recording liquid is discharged in parallel to the base plate having the electrothermal converting element arranged therefor (that is, an edge-shooter; see FIG. 21), and the method in which recording liquid is discharged perpendicularly to the base plate having the electrothermal converting element arranged therefor (that is, a side shooter).
Here, for the liquid discharge recording head thus structured, there is a fear that the recording performance will deteriorate due to abnormal conditions that may be brought about in the electric pulses that become electric signals, the bubbling condition of the recording liquid, or the like, when the temperature of the recording element base plate becomes excessively high during recording operation. Therefore, it is generally practiced to provide some heat radiation means in the liquid discharge recording head.
For the edge shooter type liquid discharge recording head, for example, the supporting base plate, which is formed of aluminum, aluminum alloy, ceramics, or some other material that serves as a heat radiating member, is often bonded to the recording element base plate formed of an Si material as described earlier.
On the other hand, for the side shooter type liquid discharge recording head, there is a simple method in which heat is radiated by means of recording liquid discharged from the recording liquid retaining medium through the backside of the recording element base plate. Further, in the liquid discharge recording head of the side shooter type in which the temperature rises more readily due to the recording elements being arranged in high density, there is a method in which the-supporting base plate serves as the heat radiating member with a comparatively large contact arca, and the recording element base plate is bonded and fixed to such supporting base plate.
In recent years, ink jet recording apparatuses have been widely and rapidly developed and used in various fields. Moreover, the recording capacity of such apparatuses has been increased, for causing an increased consumption of recording liquid. Along with this, the demand is increasing rapidly for an ink jet recording apparatus having a larger capacity of recording liquid storage.
However, as described above, the liquid discharge recording head having the recording liquid storing portion integrally contained therein has automatically a limit to the capacity of recording liquid storage. Therefore, if a large amount of recording liquid should be consumed, it becomes necessary to replace the liquid discharge recording heads frequently, which is not only troublesome for the operator to carry on the operation, but also brings about the drawback that the consumption costs of expendables become higher.
To counteract this, if the capacity of the recording liquid storage is increased, the weight of the liquid discharge recording head becomes larger, making the inertia generated by the carriage scans larger accordingly, which not only spoils the stability of carriage scans so as to deteriorate printing quality, but also brings about the drawback that the liquid discharge recording apparatus becomes larger as a whole to accommodate the large recording liquid storing chamber mounted on the carriage.
Now, therefore, the liquid discharge recording head of the mode in which, while the weight of the recording liquid storage is restricted, the detachably mountable recording liquid storing unit, that is, the so-called cartridge holder member, is mounted and made easily exchangeable, is widelyused. With the structure that holds such a cartridge tank on the holder member, it becomes easier to replenish the recording liquid, and the operating cost of printing is made comparatively small. Also, it is possible to obtain an advantage that the space needed for containing the recording liquid is made smaller so that the liquid discharge recording apparatus can be downsized.
However, in the liquid discharge recording head of this type, it is necessary that the recording supply paths be connected when bonding the recording unit and the recording liquid storing unit. As a result, a sealing member and bonding process are needed, among others.
It is also necessary to arrange the structure so that bonding between the recording unit and the recording liquid storing unit should not be released to allow recording liquid in the recording liquid storing unit to leak, even when the liquid discharge recording head receives shocking force in such an event that the liquid discharge recording head is caused to drop off or the like. Furthermore, it is necessary to avoid such a problem that recording liquid may spread out from the connecting portion of the recording liquid supply paths or that bubbles are trapped at the junction of the recording liquid connectors, among some others.
Therefore, with a view to solving the problems enumerated above, the recording unit and recording liquid storing unit are bonded by screws or the like for fixing them strongly for the liquid discharge recording head of the mode in which the recording unit and the recording liquid storing unit are bonded. However, in terms of the head cost, such as the increased costs of parts, the increase steps of the manufacturing process, the process of inspection additionally needed, and reliability as well, this measure is not favorable after all.
On the other hand, for the liquid discharge recording head of the mode in which recording liquid is supplied from an external recording liquid storing chamber to the recording unit, that is, more precisely, recording liquid is supplied to the recording unit from an external recording liquid storing chamber through the recording liquid storing unit, which is bonded to the recording unit to retain recording liquid temporarily, there is a certain degree of freedom in the installing position of the external recording liquid storing chamber, which presents advantages, such as that the layout of the liquid discharge recording apparatus can be designed efficiently, and also, the capacity of the external recording liquid storing chamber can be made larger. Furthermore, in the mode in which the external recording liquid storing chamber and the liquid discharge recording head are connected by a tube member or the like, the structure is arranged to maintain the negative pressure in the liquid discharge recording head by the water head difference between the discharge port surface of the liquid discharge recording head and the water level of the external recording liquid storing chamber. Therefore, unlike the mode in which a negative pressure means is used, such as the recording liquid absorption type or mechanical type, or the one that adopts a pit-in recording supply, this structure can be arranged very simply to make it possible to structure the apparatus at lower costs as a whole.
As has been described, there are various modes of recording liquid supply for the liquid discharge recording head, and it has been practiced conventionally to provide the liquid discharge recording heads of various modes in agreement with the required specifications of the liquid discharge recording apparatuses.
Under such circumstances, various types of liquid discharge recording head groups are produced inevitably, necessitating enormous amounts of investments in facilities, and complicated production control and management, so that productivity is significantly deteriorated.